Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of synovial tissue, leading to destruction of the joint architecture. It is recognized that cytokines such as tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) play a role in joint inflammation and cartilage damage observed in RA. IL-6 is a pleiotropic cytokine with biological effects on many cell types. IL-6 is often regarded as being downstream of TNF or IL-1 in inflammatory cytokine cascades and may therefore represent a common pathway factor in a wide range of inflammatory processes. Blockade of IL-6 signaling therefore offers the potential to ameliorate multiple pathogenic features of RA and other inflammatory diseases.
Therapeutic methods using IL-6R antagonists are mentioned in U.S. Pat. Nos. 5,888,510; 6,723,319; and 2001/0001663. Exemplary anti-IL-6R antibodies are described in U.S. Pat. Nos. 7,582,298; 6,410,691; 5,817,790; 5,795,695; 6,670,373; and 7,582,298.